In the known art, analog-type watches comprise a button available to the user for time setting operation. The time setting button allows to move the pointers (also called ‘hands’), namely the hour pointer and the minute pointer. The time setting operation usually requires to pull the time setting button which may involve damage to the nails of the user. After effective time setting, the time setting button must be pushed back into the stowed position. The operation of pushing back the time setting button may also involve a small inadvertent turn of the time setting button, and the resulting setting may thus be not accurate.
There is therefore a general need to render more reliable and also simplify systems and methods of time setting of such analog-type watches.
Also, most known analog-type watches have a reduction gear linking the hour and minute pointers. A way to simplify the structure of analog-type watches is to decouple hour and minute pointers. In this configuration, each of hour and minute pointers are controlled independently via a stepper motor, as disclosed in document U.S. Pat. No. 5,299,177. This simplifies the mechanic arrangement and allows enhanced functionalities but requires more complex electronic control.
In this configuration, however, the risk of inadvertent leap of one of the pointer is increased, for example in case of shock, electromagnetic interference or in case of low power supply. When the pointers are controlled in open loop mode, (i.e. without any position sensing feedback, only with a software zero-position), this may lead to a deviation between the assumed position (from the watch controller standpoint) and the actual position of the pointer(s). This situation requires a re-calibration of the pointer position with regard to a reference position (usually 12:00).
Also, when the power supply has been interrupted, the controller may have lost the knowledge of the positions of the pointers.
Finally, at first power up of the controller of the watch, the positions of the pointers are, in the absence any position sensing device, completely unknown.
It is to be noted that each of the independently controlled pointer has, at least for calibration purposes, a particular reference position, called in the present disclosure ‘ref-position’.
Therefore, there is a need to bring new solutions to time setting and calibration of pointers in analog-type watches with pointer independent control.